Re: question on dbazine article
- From: Jared.Still@xxxxxxxxxxx
- To: oracle-l@xxxxxxxxxxxxx
- Date: Thu, 26 Feb 2004 10:52:40 -0800
Re the freelists: there isn't enough information provided in the article
to do
anything but guess as to why it worked.
My guess is that the add'l freelists on the index gave some relief due to
a monotonically incrementing key.
Jared
"zhu chao" <chao_ping@xxxxxxxxxxx>
Sent by: oracle-l-bounce@xxxxxxxxxxxxx
02/26/2004 05:16 AM
Please respond to oracle-l
To: <oracle-l@xxxxxxxxxxxxx>
cc: "Yong Huang" <yong321@xxxxxxxxx>
Subject: question on dbazine article
http://www.dbazine.com/burleson20.shtml
I often visit dbazine and read articlles there, on this issue, I have some
questions:
question to that article:
1. he said:
alter system set optimizer_index_cost_adj=20;
alter system set optimizer_index_caching=65.
but in fact, these parameters cannot be modified online. How did he do
that?
2.Implement cursor_sharing=force
According to wait event based tuning, tuning something that is not the
bottleneck does not helps much. In his case, euqueue wait and full table
scan caused most of the problem. Would change cursor_sharing be the
solution of his problem?
3. question about add freelists;
He has 450 users inserting records, even if one person can insert a
record every 3 seconds, it is only possible that there is 150 new records
per second. Can't oracle process 150 record insert per second even if only
1 freelists? I did a small test with 300 concurrent session doing insert
into a table, each insert a table after 3 second sleep. and this is the
statspack report:( i removed the plsql locker timer event from statspack
via modifying stats$idle_event).
Top 5 Wait Events
~~~~~~~~~~~~~~~~~ Wait %
Total
Event Waits Time (cs) Wt
Time
-------------------------------------------- ------------ ------------
-------
log file parallel write 25,955 2,345
90.72
control file parallel write 146 109
4.22
db file parallel write 168 55
2.13
buffer busy waits 30,761 34
1.32 --only a few percent of that.
log file switch completion 4 22 .85
Regards
Zhu chao.
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